While the safety benefits on larger boats are obvious, I think lifelines on many small boats present more of a hazard than a safety enhancement. They are usually at just the right height to flip you over the side if you lose your balance. I can appreciate the need for them on a small flush deck boat but on a conventional cabin w/side deck arrangement the side decks are very narrow on a small boat. While lifelines on the leeward side can provide a modicum of protection, who goes forward on the low side on a small boat when it's blowing like stink? You usually go forward on the high side, where the lifelines will restrict your passage; they force you to lean inward and impede your balance keeping ability.
IMHO, it is far better to have plenty of grab rails and hand holds on a small boat. A small boat is just that: small. You do not have great distances to traverse. You can make sure that a securely mounted grab rail is always within reach.
And a sturdy toe rail will do far more to keep you aboard if you are sliding to leeward on the deck than questionable lifelines at knee height. Even a 1-1/2 inch toe rail can keep you from going over. (How much of a toe hold do rock climbers need? Not much.)
I know of a number of small boat owners who have chosen to remove their lifelines and stanchions for these very reasons. The improvement in looks is just a bonus. Another factor to consider is that OEM lifeline stanchion installations on small boats often leave a lot to be desired as far as strength goes. The installation needs to be beefed up to be just as strong as that on a larger boat. An adequately strong lifeline installation on a small boat can look out of proportion.
I rarely, if ever, have to go forward on my boat in rough weather sinced I have all lines led back to the cockpit, but I feel very safe and secure when I choose to do so because of great non-skid, adequate hand rails, and sturdy toe rails.